A flip-chip method is a chip-interconnect technology, and is also an ideal chip-bonding technology. International Business Machines Corporation (IBM) developed and used a flip-chip technology more than 50 years ago. However, it is until recently that the flip-chip method became used in packaging high-end devices and in high-density packaging. Currently, the flip-chip packaging technology has been more widely used, with diversified packaging forms and increased demands.
However, in an existing flip-chip method, the quality of solder layers is undesirable, and adjacent solder layers may be connected with one another. The disclosed methods and structures are directed to solve one or more problems set forth above and other problems in the art.